Remote-controlled vehicle which travels on conductors and which can pass over obstacles by means of temporary support rotors

ABSTRACT

A remote-controlled vehicle adapted to be mounted on at least one conductor and to pass over an obstacle encountered thereon. The vehicle includes: a frame, inspection systems, motors used to move the vehicle, a remote control system, at least two carrying arms pivotally mounted to the frame and exerting a pressure in the direction of the conductor(s) for suspending the frame to the conductor(s) and two opposing wheels attached to each carrying arm in order to enable the vehicle to travel along said conductor(s) while suspended. The axis of rotation of each of the wheels is inclined in relation to the vertical axis and at least one of the wheels is actuated by the motors. At least one temporary support rotor is equipped with at least two pivoting blades disposed above the corresponding conductor in order to temporarily support the vehicle when one of the wheels encounters an obstacle.

FIELD OF THE INVENTION

The present invention relates to an important improvement to the familyof small remote controlled vehicles (also know as ROV's or “RemotelyOperated Vehicles”) which are adapted to travel on aerial conductorssuch as those used in the field of transmission of electrical energy andwhich may or may not be under live electrical conditions. In particular,the invention relates to mechanical carriers that are used to transportsensors or existing equipment so as to have access to different parts ofsaid conductor.

BACKGROUND OF THE INVENTION

The present world context regarding the exploitation of an electricalenergy transmission network is the following: ageing components,increasing demand for energy, deregulation and opening of markets,increasing pressure by clients for quality and reliable energy. Theelectrical utilities are therefore required to know precisely the stateof their transmission network in order to apply the principles ofpreventive maintenance for safekeeping the reliability of the systems.The evaluation of the state of a component is evaluated, inter alia,through measurements by means of sensors. With regard to the gatheringof information, numerous sensors have been developed but the positioningof these sensors, in order to access the components, often remains animportant challenge. The use of remote-controlled vehicles (ROV) forthis task in order to achieve the inspection of circuits of conductorsis therefore very appropriate.

Many vehicles of the ROV type have been developed in the past. A quickoverview will bring to the fore the characteristics and disadvantages ofthe main ones.

Referring to FIG. 1, there is shown a remote-controlled line chariot forthe inspection of circuits with a simple conductor and which is theobject of U.S. Pat. No. 6,494,141 (MONTAMBAULT et al.) Thisremote-controlled vehicle is very efficient, compact, relatively lightand easy to use. It also has a good traction force which renders it veryversatile. It is a third generation prototype that has proven many timesover its efficiency, its mechanical robustness and its robustness towork under live electrical conditions (315 kV, 1000 A). It allows thede-icing of overhead ground wires and of conductors, thermographic andvisual inspections and the measurement of the electrical resistance ofjoints. It travels on simple conductors regardless of their diameters.However, this type of ROV is only capable to pass over mid-span tensionjoints, but cannot pass over on its own pylons or vibration dampers orspacers. It has to be dismantled when it reaches an insurmountableobject and has to be put back together again on the other side of theobstacle.

Referring to FIGS. 4 and 5, there are shown different chariots used forthe evaluation of a level of corrosion in steel cables or that allow tocarry out the method of “pulleys-cradles”. FIG. 4 shows a chariotcommercialized by the firm Furukawa. FIG. 5 shows another similarchariot made by the firm Fujikura. These chariots use old technologies.In fact, the chariots use two wheels with a motor. They have a very lowtraction force. They cannot work with under live electrical conditions.They travel on a simple conductor, without being able to pass overpylons or spacers.

Referring to FIG. 6, there is shown a robot for installing warningmarkers. It is a voluminous and heavy prototype. It is dedicated to theinstallation of warning markers on overhead ground cables (in general).

The above-mentioned concepts may sometimes be efficient for certainprecise tasks but are often heavy, sometimes fragile and may rarely workunder live electrical conditions. However, the principal disadvantage ofthese concepts is their inability to pass over obstacles that arelocated on the conductors, such as vibration dampers, and even less tochange spans by passing over the elements which hold the conductor toeach pylon. They are therefore all restricted to intervene only betweentwo pylons or to be removed and then reinstalled on the other side ofthe insulator strings by a human operator. One can therefore easilyimagine the advantage of providing an ROV concept that could be used onmany spans to inspect, for example, several kilometers of conductorswithout requiring direct human intervention.

Other concepts, having in particular the same object, have however beendeveloped. Indeed, below, there are described some experimentalprototypes for passing over obstacles on simple conductors.

Referring to FIGS. 2 and 3, there is shown prototypes or concepts thatcan travel on a simple conductor and can pass over pylons (insulatorstrings and vibration dampers). FIG. 2 shows a prototype by the firm TVA(Tennessee Valley Authority). FIG. 3 shows another prototype by NSI-NASA(Sewada et al.) These apparatus are very large, very complex anddifficult to install. It is not clear if they are able to work underlive electrical conditions. It seems that these apparatus were notdeveloped in consultation with the eventual users because they are muchtoo large and complex to be usable in a network in a reliable manner.The speed of passing over the obstacles is not fast, because of thecomplexity of the mechanisms that are used. The price of these apparatusis possibly disadvantageous because of the complexity of the systems.

Referring to FIGS. 7 and 8, there is shown respectively a motorizedaerial basket (Hydro-Quebec TransEnergie) and one that is non-motorized(Italy). These prototypes are not vehicles of the ROV type because theyare used to transport linemen as they are mounted on conductors. Theseconcepts allow them to move on the conductor bundles and to pass overthe spacers and pylons (insulator strings). The mounted operator mustthen activate levers and to deploy on his own certain supplementarywheels in order to have enough support on each side of the obstacles.The operation requires a relatively long time.

SUMMARY OF THE INVENTION

The present invention manages to reconcile the advantages of each of theabove-described categories of vehicles by achieving the passing over ofobstacles in an easy, fast and reliable manner.

The present invention therefore relates to a remote-controlled vehicleadapted to be mounted on at least one conductor cable and for passingover an obstacle on said at least one conductor, the vehicle comprising:

-   -   a frame;    -   inspection systems mounted on the frame for inspecting the one        or more conductors;    -   motor means for displacing the vehicle on the one or more        conductors;    -   a remote control system for controlling the inspection systems        and the motor means;    -   at least two carrying arms positioned on opposite sides of the        one or more conductors, the carrying arms being pivotally        attached to the frame and exerting a pressure in a direction of        the one or more conductors for suspending the frame onto the one        or more conductors;    -   at least two opposing wheels, each wheel being attached to each        carrying arm for enabling the vehicle to travel along the one or        more conductors while maintaining the vehicle suspended, each        wheel having an axis of rotation that is inclined with respect        to a vertical axis, at least one of said two wheels being        activated by the motor means; and    -   at least one temporary support rotor provided with at least two        pivoting blades which are disposed above the corresponding        conductor for temporarily supporting the vehicle when one of the        wheels encounters the obstacle;    -   thereby, in use, when the vehicle travels on the one or more        conductors and one of the wheels encounters the obstacle and        looses contact with the one or more conductors, the blades        temporarily lean on the conductor and/or the obstacle and        support the vehicle so as to prevent the vehicle from falling        and then allow the wheels to contact once again the one or more        conductors once the obstacle is passed over.

Preferably, the temporary support rotor has three blades distributed allaround the disk of the rotor. This rotor may be coaxially mounted on oneof the wheels and pivots independently with respect to the wheel onwhich the rotor is mounted. The rotor may also be provided with apassive indexation position system or a return spring that maintains areference position of the blades when approaching the obstacles. Thecarrying arms may be provided with spring systems in order to exert therequired pressure.

The invention as well as its numerous advantages will be betterunderstood by the following non-restrictive description of preferredembodiments of the invention made in reference to the appended figures.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 to 8 are perspective views of different apparatus known in theprior art and that are adapted to be mounted on conductor cables.

FIG. 9 is a partial perspective view of a carrying arm and a temporarysupport rotor mounted on a conductor cable according to a preferredembodiment of the present invention.

FIG. 10 is a top view of the carrying arm and of the temporary supportrotor shown in FIG. 9.

FIGS. 11A, 11B, 11C and 11D are partial perspective views of thecarrying arm and temporary support rotor shown in different stages whilepassing over an obstacle on the conductor cable.

FIG. 12 is a perspective view of a temporary support rotor that isleaning on a clamp of a conductor according to a preferred embodiment ofthe present invention.

FIG. 13 is a partial side view of the carrying arm and of the temporarysupport rotor shown in FIG. 9.

FIG. 14 is a perspective view of a remote-controlled vehicle mounted ontwo inferior conductor cables of a bundle of four conductors andprovided with four temporary support rotors, before the passage of aspacer, according to a preferred embodiment of the present invention.

FIG. 15 is a perspective view showing the bottom of theremote-controlled vehicle shown in FIG. 14.

FIG. 16 is a perspective view of a remote-controlled vehicle providedwith temporary support rotors for a quadruple bundle according to apreferred embodiment of the present invention.

FIG. 17 is a perspective view of a remote-controlled vehicle providedwith temporary support rotors adapted for a double bundle according to apreferred embodiment of the present invention.

FIG. 18 is a perspective view of a remote-controlled vehicle providedwith a temporary support rotor adapted for a simple conductor accordingto a preferred embodiment of the present invention.

FIG. 19 is a bottom view of the remote-controlled vehicle shown in FIG.18.

FIG. 20 is a perspective view of a remote-controlled vehicle providedwith temporary support rotors adapted for a triple bundle according to apreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 9 to 20, there is shown a remote-controlled vehicle 1adapted to be mounted on at least one conductor cable 3 and for passingover an obstacle 5 on the one or more conductors 3, according to apreferred embodiment of the invention. The vehicle 1 includes a frame 7,inspection systems 9, 10 mounted on the frame 7 for inspecting the oneor more conductors 3, motor means 11 for moving the vehicle 1 on the oneor more conductors 3, a remote control system 13 for controlling theinspection systems 9, 10 and the motor means 11, and at least twocarrying arms 15 positioned on opposite sides of the one or moreconductors 3. The carrying arms 15 are pivotally attached to the frame 7and exert a pressure in the direction of the one or more conductors 3for suspending the frame 7 onto the one or more conductors 3. Thevehicle 1 also has at least two opposite wheels 17. Each wheel 17 isattached to each carrying arm 15 for allowing the vehicle 1 to travelalong the one or more conductors 3 while maintaining the vehicle 1suspended. Each wheel 17 has an axis of rotation that is inclined withrespect to a vertical axis and at least one of the two wheels 17 isactivated by the motor means 11. The vehicle 1 further includes at leastone temporary support rotor 19 provided with at least two pivotingblades 21 positioned above the corresponding conductor 3 for temporarilysupporting the vehicle 1 when one of the wheels 3 encounters theobstacle 5. Thereby, in use, when the vehicle 1 travels on the one ormore conductors 3 and one of the wheels 3 encounters the obstacle andlooses contact with the one or more conductors 3, the blades 21temporarily lean on the conductor 3 and/or the obstacle 5 and supportthe vehicle 1 so as to prevent the vehicle from falling and then allowthe wheels 3 to contact once again the one or more conductors 3 once theobstacle 5 is passed over.

The aerial electrical conductors 3 on which travels the vehicle 1 may ormay not be connected to electrical power and carry a current. Thefundamental particularity of this vehicle 1 is that is has the capacityto pass over in a very simple, autonomous and reliable manner theobstacles 5 that are present on the conductors 3. These obstacles 5 arenamely vibration dampers of different types, spacers in the case ofconductor bundles and especially suspension elements (clamps andinsulator strings) that are present on each pylon and that are used tosupport the one or more conductors 3. This vehicle 1 can therefore beused to transport in a remote-controlled and/or autonomous manner amultitude of sensors used for the inspection and for the maintenance ofline components (cameras, measurement instruments, etc.) and on severalspans, thereby covering a large distance.

The principal application of the prototype according to a preferredembodiment of the present invention is for a quadruple conductor bundle3, such as those used on the Hydro-Québec network for lines at 735 kV.It is in fact firstly for this configuration of conductors that theconcept was experimentally validated by means of a functional prototype,which is shown on FIG. 16. Therefore, the figures illustrating theconcept are taken from this type of application. However, as it will beseen further below, the invention that is claimed is general enough tobe adapted to many other types of configuration circuits, either for asingle conductor, or for bundles of two, three, four or six conductors.

Referring to FIG. 9, there is shown certain elements that are in thiscase carried by a carrying arm 15 that is independently connected to theframe 7 of the vehicle 1. There is shown a wheel 17 that is held againstthe conductor 3 in a very inclined manner with respect to a verticalaxis and that is pushed against the conductor 3 by means of springs 29(see FIG. 16) that pull on the carrying arm 15, which can then pivotaround pivot 16 which is parallel to conductor 3, in order to increasethe available traction force and to increase the stability of the holdon the conductor 3. The wheel 17 may be a drive wheel in order toprovide traction on the conductors 3 or it can also act as a passivepressure wheel. In the case where the wheel 17 is a drive wheel, it ispreferable to have a traction motor 11 for each drive wheel. This motor11 is mechanically connected to the wheel 17 by means of gears or aspeed reducing belt 12.

Referring to FIG. 13, the carrying arm 15 also includes a rotor 19,which also has a very inclined rotation axis, and at least two blades 21whose plane passes above the one or more conductors 3. These rotors 19are preferably coaxially mounted with the wheels 17, which may betraction or pressure wheels. The function of these temporary supportrotors 19 is to temporarily support the vehicle 1 or a part of thevehicle when some of the wheels 17 pass over an obstacle and risk toslide and loose contact with the conductors 3. The blades 21 of theserotors 19 are therefore correspondingly dimensioned with the dimensionsof the obstacles 5 and the encounter of one of the blades 21 of therotor 19 with the obstacles 5 starts the rotation of the rotor 19 sothat the next blade 21 passes over the obstacle 5 and goes on to lean onthe conductor 3. Once the obstacle 5 is passed over, the wheel 17 isguided by the blades 21 of the one or more rotors 19 towards the one ormore conductors 3 and once again it is leaned against it. This sequenceof events is schematically illustrated by FIGS. 11A to 11D and 12 thatonly show the elements related to a single carrying arm 15.

The temporary support rotors 19 may include a passive indexationposition system (not illustrated) or a return spring 20 that maintains areference position of the blades when approaching the obstacles so as toensure that they return to that position or to an equivalent positiononce the obstacle 5 is passed over. In the embodiment depicted in FIG.12, the return spring 20 produces a leaf spring effect. The rotation ofthe rotor 19 is therefore not activated by a motor.

Preferably, the shape of the wheels 17, as the one shown in FIG. 13,allows accommodating different diameters of conductors 3 by means of aprofile having a central groove 23 and a rounded edge 25 forfacilitating the passing of the obstacles 5. The wheel 17 may bepreferably made of rubber of low hardness in order to maximize thefriction coefficient and the performances on a humid conductor. Thewheels 17 may also be made of polyurethane but this material is lessefficient on humid conductors. A metallic additive may be incorporatedin the rubber in order to increase the electrical conductivity of thevehicle 1. The external edge 27 of the wheels 17 may be rounded and madeof plastic material so as to provide not much traction on the obstaclesthat are passed over for ensuring that the conductor 3 slides and comesback to its position in the middle of the central groove 23 once theobstacle 5 is passed over.

Preferably, each of the motors 11 include a control system of the speedand motor or traction force in order to adjust the speed of the vehicle1.

Referring to FIGS. 14, 15 and 16, there is shown a first application ofthe vehicle TSR (temporary support rotor) that is adapted to travel on aquadruple bundle of conductors 3, by resting on the two conductors 3 onthe bottom. This vehicle 1 has the same characteristics described aboveand joins four identical arms to a common frame 7. The vehicle 1therefore includes four drive wheels 17 positioned in two pairs,therefore forming a front axle and rear axle. Temporary support rotors19 are coaxially mounted on each of the wheels 17. Springs 29 biasedbetween two arms 15 of a same axle apply a force that tends to bringthem one against the other, thereby transferring a lateral contact forcefrom the wheels 17 onto the conductors 3. Elastic bands or any othersimilar spring means may be used instead of the springs 29 in order toaccomplish the same function, as it will be understood by personsskilled in the art.

FIG. 15 shows different sub-systems inherent to a complete functionaland autonomous vehicle 1. Preferably, the one or more motors 11 used areof the electric type and are powered by batteries housed in housings.The batteries may be rechargeable such as the hydride metal nickel type.The power source chosen is sufficient for powering the installedaccessories, such as the systems of cameras 9 or resistance measurementequipment 10. However, it is also possible to use a gas generator as apower source in order to obtain greater autonomy.

Preferably, the vehicle has mounted electronic 13 necessary for its gooduse as well as a telecommunication system for its remote control, withan antenna 14 and a frequency jump receiver. The mounted electronicequipments are protected from the electromagnetic fields by a Faradaycage and are optimized to achieve mechanical robustness.

The configuration of vehicle 1 itself may vary greatly, by recombiningeach of the different elements described above in order to adapt it todifferent type of conductors 3. A few figures are provided as examples,in order to illustrate the different possibilities.

It is possible, as shown in FIG. 17, to only have two carrying arms 15,and therefore two drive wheels 17 and two rotors 19. This concept isusable on double bundle and quadruple bundle, such as the four rotorversion described above.

One of the simplest but very interesting modifications of the TSRconcept is shown in FIG. 18 and is meant to travel on a simple conductor3 while passing over the obstacles 5, which are encountered thereon. Onethen always uses four pivoting carrying arms 15 but only two tractiondrive wheels 17 provided with two temporary support rotors 19 withblades 21. Thereby, two of the four arms 15 only support the pressurewheels 18 that may or may not be drive wheels. The shape of the pressurewheels 18 is somewhat different in order to conform with the shape ofthe traction wheels 17. This allows to properly position the conductor 3in the groove of the traction wheels 17. Of course, one may adapt thisprinciple of pressure wheels 18 for a vehicle 1 adapted to travel onconductor bundles 3 instead of a simple conductor 3.

The carrying arms 15 of the pressure wheels 18 may be positioned indifferent planes than those of the traction wheels 17, as shown in FIG.19.

The same concept may also be used on a triple bundle (see FIG. 20), byleaning onto the lower conductor. Lastly, other combinations are easilyconceivable (not illustrated): for example, one may take out onepressure wheel 18 from the last concept presented above and position itin between the traction or drive wheels 17, which would then be bothlocated on the same side of the conductor 3, both opposed to thepressure wheel 18.

Furthermore, even though the rotor 19 is preferably mounted directly onthe top of one of the wheels 17, it is also conceivable that the rotor19 be mounted directly on one of the carrying arms 15 and not on a wheel17. It is also possible that the rotor 19 be mounted separately anddirectly on the frame 17 of the vehicle without being mounted on a wheel17 or on a carrying arm 15 provided with a wheel 17. For example, therotor 19 may be mounted on a carrying arm 15 that is not provided with awheel and functions substantially in the same way as explained above.

Herein below there is described the performances and preferentialadvantages of the present invention. The practical conditions of usemake it imperative to pass over the obstacles by means of a mechanicalsolution that is simple and reliable. The least amount of possiblemobile pieces often implies lesser breakage risks. One also tries tominimize the use of electronics. One thereby obtains a product thatsatisfies the following criteria:

-   -   Mechanism allowing passing over obstacles without having to        stop;    -   Possibility of stopping on an obstacle if it has to be        inspected;    -   Mechanism that may pass over the obstacles by means of        mechanical systems, thereby requiring a minimum of mounted        electronics;    -   Mechanism allowing to pass over the obstacles while moving        forward and moving backward;    -   Installation and secure displacement of the vehicle on the        bundle: no possible fall and safekeeping of the integrity of the        line components;    -   Robustness and reliability in view of use conditions (transport,        mechanical shocks, etc.);    -   Robustness in view of unfavourable weather conditions (humidity,        dust, snow, moderate winds and ambient temperature);    -   Good traction force of the chariot on humid conductors and even        covered with ice (at least equal to its weight);    -   Reliability and electromagnetic compatibility of the electronics        and of the telecommunication systems while under live electrical        conditions (up to 765 kV-750 A);    -   Passing time of an obstacle which is very short (a few seconds).

The positive impact of such a vehicle may be noticed at several levels:

-   -   Facilitates the access to different spans and to difficult to        reach components;    -   Evaluation of the aerial joints (a diagnostic of the state of        the weak links of the network, which is up to now difficult to        achieve, particularly on the bundle circuits);    -   Optimisation of the maintenance costs (optimal and objective        maintenance decisions, less expensive work method, reduction of        intervention time, on-site inspection while under live        electrical conditions, minimizing of expensive taking of        samples);    -   Minimizing of the planned service interruptions (new methods of        working while under live electrical conditions) and not planned        (better knowledge of the state of the network and preventive        maintenance);    -   Increased reliability of the network by means of the archiving        and follow up of the evolution of the state of the network;    -   Health and security of the workers by separating the operator        from the danger zone;    -   Improvement in the productivity and the efficiency of the        inspections.

Although the present invention has been described above by preferredembodiments thereof, it is to be understood that the invention is notlimited to these precise embodiments and that various changes andmodifications may be effected therein without departing from the scopeor the spirit of the present invention.

1. A remote-controlled vehicle for travelling on aerial conductors,comprising: a frame; inspection systems mounted on the frame forinspecting at least one conductor; motor means for displacing thevehicle on said conductor; a remote control system for controlling theinspection systems and the motor means; at least two carrying armslocated on opposite sides of said conductor, the carrying arms beingpivotally attached to the frame and exerting a pressure in a directionof said conductor so as to enable the frame to be suspended from saidconductor; at least two opposing wheels, each wheel being attached toeach carrying arm for enabling the vehicle to travel along saidconductor while maintaining the vehicle suspended therefrom, each wheelhaving an axis of rotation that is inclined with respect to a verticalaxis, at least one of said two wheels being activated by the motormeans; and at least one temporary support rotor mounted with one of thewheels and provided with at least two pivoting blades, disposed abovethe corresponding conductor, for temporarily supporting the vehicle,wherein, when the vehicle travels on said conductor and one of theblades encounters an obstacle, the rotor starts to rotate so thatanother one of the blades passes over the obstacle and temporarily restson the conductor and/or the obstacle and supports the vehicle, causingthe respective wheel to temporarily loose contact with said conductor,and, once the wheel passes over the obstacle, the blades guide therespective wheel towards said conductor so as to contact said conductoronce again.
 2. The vehicle according to claim 1, wherein each temporarysupport rotor comprises three blades distributed around each rotor. 3.The vehicle according to claim 1, wherein each rotor is coaxiallymounted on each wheel and independently pivots with respect to the wheelon which the rotor is mounted.
 4. The vehicle according to claim 1,wherein said at least two carrying arms are biased by spring means thattend to bring together the carrying arms one towards the other, therebytransferring a lateral contact force from the wheels on to said at leastone conductor.
 5. The vehicle according to claim 1, wherein each rotoris provided with a return spring for maintaining a reference position ofeach blade when approaching the obstacle.
 6. The vehicle according toclaim 1, wherein each wheel has a central groove for receiving variousdiameters of conductors and a rounded edge for facilitating the passageof the obstacles.
 7. The vehicle according to claim 1, wherein the motormeans comprise electric motors and are powered by batteries.
 8. Thevehicle according to claim 7, wherein the batteries are rechargeablebatteries of the nickel metal hydride type.
 9. The vehicle according toclaim 1, wherein the motor means are powered by a gas generator.
 10. Thevehicle according to claim 1, wherein the inspection systems comprise acamera system and a resistance measuring system.
 11. The vehicleaccording to claim 1, wherein the vehicle is provided with four carryingarms positioned two by two on each side of the one or more conductors,each carrying arm being respectively provided with a temporary supportrotor.
 12. The vehicle according to claim 1, wherein the vehiclecomprises four wheels, two of which are drive wheels that are powered bythe motor means by means of a belt or gearings.